Dyestuff and process of making same.



FRANCIS I. QAKES, OF NEW YORK, N. Y.

DYEST'UFF AND PROCESS OF MAKING SAME.

Specification of Letters Patent.

Patented Nov. 26, 1907.

Application filed January 13. 1906. Serial No. 295.851-

To all whom it may concern:

Be it known that I, FRANcIs J. OAKES, a citizenof the United States, and a resident of the borough of Manhattan, city, county, and State of New York, have invented certain new and useful Improvements in Dyestuffs and Processes for Producing the Same, of which the following is a specification.

Vegetable coloring matter extracted from logwood and commonly designated as hematoxylin has been, in practice, sufficiently oxidized by bringing atmospheric air into contact with a solution thereof, the resulting product being well known as hematin. The aforesaid process for producing hematin imparts thereto, however, an acid character, which is not, in all cases, desirable, as for instance in the process of therewith dyeing skein silk black in a soap bath, in which case the said acidity of the hematin may unduly decompose the soap, thereby undesirably setting free fatty acids, which results in what is known in the art as breaking the soap, the injuriousness of which, both to the bath andthe article dyed are well understood by those skilled in the art. My researches have demonstrated that the aforesaid undesirable acid condition of the hematin for the purposes described and other analogous purposes may be largely, if not entirely, overcome and a practicable neutrality imparted by adding to thehematin, at the conclusion of the said oxidation process, a suflicient quantity of an alkaline nitrite, either in the form of a dry salt, or, preferably in a watery solution, which, combining with the acid, results in the production of the practically neutral hematin desired for the specific purpose above referred to.

My said process is performed as follows. I first produce in any convenient manner a solution of the hematoxylin. Into this I inject oxygen, preferably as contained in atmospheric air, until the hematoxylin has been changed by the consequent reactions into hematin. I then add to this solution of hematin the said alkaline nitrite until said hematin has become neutral.

I am aware that hematoxylin has been previously oxidized into hematin; also that hematoxylin has been treated with nitrite of soda as a substitute for such oxidation, but I believe myself to be the first to treat hematin with such nitrite.

What I claim as new and desire to secure by Letters Patent is the following, viz:

The above described process for producing an improved dye stuff which consists in first making a solution of hematoxylin, next in jecting into such solution oxygen until the hematoxylin has been changed to hematin and finally adding to the solution an alkaline nitrite until said hematin has become neutral.

FRANCIS J. OAKES. lVitnesses:

WALTER D. EDMoNDs, PHILIP C. PECK. 

